Process for the manufacture of fibrous mixtures having superior antistatic characteristics

ABSTRACT

A PROCESS FOR THE MANUFACTURE OF A FIBROUS MIXTURE HAVING SUPERIOR ANTISTATIC CHARACTERISTICS COMPRISING THE STEPS OF (1) SUBJECTING A FIBROUS MATERIAL TO DEPOSITION OF A NOBLE METAL CATALYST ON THE SURFACE OF SAID FIBROUS MATERIAL THEREBY SENSITIZING, CONDITIONING AND ACTIVATING SAID SURFACE, (2) DRYING THE CATALYST-DEPOSITED FIBROUS MATERIAL, (3) MIXING THE THUS CATALYST-DEPOSITED AND DRIED FIBROUS MATERIAL WITH A NON-CATALYZED FIBROUS MATERIAL FORMING A FIBROUS MIXTURE, (4) SUBJECTING SAID MIXTURE TO STRETCHING, SHRINKING, BULKING, TEXTURIZING, WEAVING, KNITTING, OILING OR DYEING, AND (5) SUBJECTING SAID MIXTURE TO A METAL-DEPOSITION TREATMENT IN A CHEMICAL BATH CONTAINING A METAL SELECTED FROM THE GROUP CONSISTING OF SILVER, COPPER, NICKEL, TIN, PALLADIUM, COBALT, ZINC, CHROMIUM, AND GOLD, THEREBY DEPOSITING SAID METAL EXCLUSIVLEY ON THE FIBROUS MATERIAL IN SAID MIXTURE CONTAINING SAID DEPOSITED CATALYST, IS DISCLOSED.

United States Patent Oflice US. Cl. 117-47 R 15 Claims ABSTRACT OF THE DISCLOSURE A process for the manufacture of a fibrous mixture having superior antistatic characteristics comprising the steps of 1) subjecting a fibrous material to deposition of a noble metal catalyst on the surface of said fibrous material thereby sensitizing, conditioning and activating said surface,

(2) drying the catalyst-deposited fibrous material,

(3) mixing the thus catalyst-deposited and dried fibrous material with a non-catalyzed fibrous material forming a fibrous mixture,

(4) subjecting said mixture to stretching, shrinking,

bulking, texturizing, weaving, knitting, oiling or dyeing, and

(5) subjecting said mixture to a metal-deposition treatment in a chemical bath containing a metal selected from the group consisting of silver, copper, nickel, tin, palladium, cobalt, zinc, chromium, and gold, thereby depositing said metal exclusively on the fibrous material in said mixture containing said deposited catalyst,

is disclosed.

This invention relates generally to the manufacture of fibrous mixtures having superior antistatic characteristics; it concerns more specifically the manufacture of fibrous mixtures containing metallized or chemically metal-deposited fibers acting as antistatic components for said mixture substantially composed of water-repellent fibers, especially thermoplastic and synthetic fibers.

The term fibrous mixture used herein throughout the specification includes fiber mixture; blended fibers; mixedly spun fibers; mixed filaments bundle; conjugate composite fiber, mixed yarn bundle; mixed fiber thread or threads; and woven and knitted fabrics.

It is a sincere desire among those skilled in the art to provide a permanent and superior antistatic characteristic to textile products such as yarns, woven and knitted fibrous products. For this purpose, it has already been proposed to employ oiling, surface resin treatment and the like. The main and predominant drawback inherent in the prior art of this kind resides in that the antistatic effect thus produced is liable to be lost during and upon repeated Washes and launderings. The antistatic effects thus obtained decreases, especially when the textile products are exposed to low humidity environment.

It has been proposed in recent years to admix synthetic fibers with metallic fibers, especially of stainless steel, for attaining a permanent and durable antistatic performance of the fibous products. The manufacture of metallic fibers is, however, highly complicated and thus costly. On the other hand, the metallic fiber has a high specific gravity, on the one hand, and only a poor stretchability when seen from the view point of clothing or the like purpose. Metallic fibers are highly difficult to mix evenly with other kind Patented Aug. 22, 1972 of fibers, such as synthetic fibers, even in the spinning process, and liable to slip off from the mixed fiber mass. A still further drawback of the metallic fiber resides in lack of thermal contraction and heat setting performances which are commonly found in synthetic fibers.

It is the main object of the present invention to provide a process for the manufacture of a fibrous mixture, the latter comprising chemically metal-deposited fibers which have a small value of specific gravity; a superior stretchability, a superior coloring characteristic and an efficient spinning performance and said mixture representing a highly durable antistatic performance, even in a low humidity environment.

It is a further object of the invention to provide a bulky fiber mixture having superior and permanent antistatic characteristics.

These and further objects, features and advantages of the present invention will become more apparent as the description proceeds.

It has already been proposed by the present applicants to provide fibrous mixtures having superior antistatic characteristics, even in a low humidity environment, by employing such a process wherein fibers are preferably upon degreasing, subjected to successive steps of sensitizing, activating and chemical metal-depositing; and the thus surface-metallized fibers preserving their original favorable values of various physical properties, such as specific gravity, strength, stretchability and spinnability are then used per se, or mixed with similar or other kinds of fibers in the course of spinning, yarn-forming, weaving or knitting.

According to our further development of the above prior improvement, it is surprisingly found that a highly effective metal coating is realized on a chemical fiber, preferably a thermoplastic fiber, when it is sensitized and activated by deposition on its surface of a noble metal catalyst, dried, subjected to a fiber-improving after-treatment such as oiling, stretching, shrinking or dyeing or the like; and then degreasing and chemically metal-depositing. In this way, the activity of the catalyst can be preserved for an extended period.

The above process can effectively be applied to various kinds of chemical fibers including those of acetate, triacetate, cuprammonium rayon, polyamide, polyester, polyvinyl, polyacrylonitrile, polyvinyl chloride, polyvinylidene chloride, polyolefin, polyurethane and their copolymers, of which acrylonitrile synthetic fibers and then those of polyvinyl chloride, polyvinylidene chloride or the like are highly effective for the desired purpose on account of the provision of a highly tight and durable metal deposit. This is apparently based on such fact that the acrylonitrile fiber has in its molecular structure at least a high polarizing group, such as CN and the like radicals and that the fiber surface represents a fine fibril structure, in addition to the very presence of fine surface undulations which are formed in the course of its dryor wet-spinning process, whereby the acrylonitrile series synthetic fibers are generally manufactured, said undulations being found highly effective for anchoring of the catalyst.

As the metal suitable for carrying out the process according to this invention, silver; copper; nickel; cobalt; tin; palladium and the like may be used, of which nickel and copper are highly recommendable. This may be at tributed to a strong autocatalytic performance possessed by these metals.

The resulting superior metallized fibers capable of obviating the aforementioned various conventional drawbacks can be, as ascertained by our profound practical experiments, processed without substantial loss of the now realized favorable performances in the field of fiber improving after-treatment whereby the fibers are subjected, as is well known, to a considerable mechanical and thermal deformation to such a degree that the deposit of the coated metal layer on the fiber proper would be substantially loosened. The term mechanical and thermal deformation as used throughout this specification is intended to include stretching, bending, twisting, frictional slippage or the like in or among fibers, or any combination thereof. When a dyeing process is employed, on the other hand, as a step of said after-treatment, the resulting color tone will frequently be injured if there be the reducing metal layer on the surface of the fiber, as was referred to hereinbefore.

The chemical deposition of metal or metallization of fibers employed as a step of the process according to this invention is realized substantially by depositing a selected metal on the fibers through the Way of a reducing separation. Therefore, the metallic coating thus produced has a strong tendency of reducing activity. When a fibrous mixture containing an amount of such metallized fibers is dyed in a conventional way, uneveness of the dyed color tone could be invited on account of practical discoloration and/ or fading of the dyestufi.

As a preferred embodiment of the invention for obviating such a defect, the process is carried out in such a way that the fibers are at first subjected to sensibilization and activation, and then the thus resulted raw fibers activated are mixed with plain or non-processed fibers, dyed and chemically metal-deposited. In this way, a fiber mixture including metal-coated fibers and representing a superior color tone without any appreciable degree of discoloration and/or fading appearing in and after the dyeing step can be provided.

By employing an admixing step of metallized fibers with plain or non-processed fibers in accordance with our prior proposal, a superior antistatic performance could be obtained with increased mixing ratio of the former, on account of correspondingly increased conductivity of the resulted fiber mixture. It has been found, however, that with an excessively increased mixing ratio of metallized fibers, a blackish and non-smart color tone will result in case of a brillant dyeing, on the one hand, and a localized glazing and glistening tone will be brought about in case of a dark color dyeing, on the other, by virtue of the very existence of an excess amount of metallized fibers. These drawbacks, if invited, will affect adversely the practical utilization of the fiber mixture in the field of clothing and interior purposes.

We have tried to provide an antistatic and bulky fiber mixture of the above kind, having a superior developing performance, as well as an improved hand feeling, by using the metallized fibers as its high shrinkage components and the plain or non-processed fibers as its low shrinkage components.

As a standard process for the manufacture of bulky yarn, the fiber is generally processed in such a way that upon thermo-slackened it is subjected to a stretching of 1.1-1.5 times at a high temperature in the order of 100- 150 C. by means of boiling water, dry heating, turbo stapler or the like, into a high shrinkable fibrous stock having 540% shrinkability which stock is then mixed with a low shrinkable fiber mass, and the resulting mixture is caused to shrink during the next succeeding step of dyeing or heat treatment, for developing the latent bulkiness into its apparent form.

It has been found according to our practical experiments that when the metallic layer, 0.01-1.0 micron thick, is subjected to a stretching in the order of about 110150% and then a later a contraction of 40%, the scale-off fastness of the metallic coating is substantially decreased than otherwise, and at the same time only a reduced contraction rate of about 2% will result upon subjecting to the regular thermo-slacking, provided that the metallized fiber has been once stretched. In a preferred embodiment of the present invention, a high shrinkable fiber mass is manufactured in such a way the fibers are subjected to thermo-slackening; degreased; sensitized and activated, and then thermally stretched to a degree of about 1.1-1.5

times to provide an activated and high shrinkable fibrous stock with 540% latent denier increase. Or alternatively, the fibers are so processed that upon being subjected to a thermal slackening, they are thermally stretched to about 1.1-1.5 times elongation; degreased; sensibilized and activated, so as to provide a similar high shrinkable fiber mass.

Then, the thus processed fiber mass is admixed evenly with a similar high shrinkable fiber mass which has not been, however, activated, yet having the same latent shrinkability of about 540%. This mixture is further admixed evenly with a still further fiber mass, having a substantially less shrinkability than that above specified and formed into yarns through spinning. These mixed-fiber yarns are subjected to a dyeing or a heat treating step, for developing the latent bulkiness, and finally treated in a chemical bath adapted for performing the metal depositing step. In this way, the activated, high shrinkable fiber components of the overall fiber mass only are formed with metallized coatings. In this case, the final mass or yarns represent a satisfactory bulkiness.

The products prepared by the aforementioned preferable mode of the process represent an evenly mixed state; substantially no discoloring and fading of the above defective kind; a superior dyeing performance; an improved coverage of the metallic coating layer; as well as a superior hand feeling.

In order to provide a sufficiently antistatic textile product consisting of said bulky yarns, the metallized fibers may be processed so as to admix them evenly in the whole mass of the textile. It has been found that with a specifically fixed rate of fiber mixture, more superior results are obtained with finer deniers of the metallized fiber and with longer lengths thereof. Therefore, it can be concluded positively that the antistatic performance of the products depends mainly upon the continuity of the admixed metallized fiber components, rather than the mixing ratio thereof.

When it is intended to provide a textile product with a superior antistatic performance under the utilization of yarns including said kind of metallized fibers, the yarn should preferably contain them in such a mixing ratio which is higher than that assuring a continuity of said fibers when seen from the point of its theoretical probability. Reference should be had to Examples 2 and 3 to be given. Further, it is not always necessary to compose the whole structure of the textile product with the said kind of yarns, but it is generally sufiicient to distribute such yarns therein.

According to our practical experiments, it has been determined that in order to secure a satisfactory degree of antistatic performance the mixing ratio of metallized fibers should be higher than 0.01 wt. percent. An employment of less mixing ratio than above specified will provide only an insufficient degree of antistatic performance.

It will be thus understood from the foregoing that when bulky yarns prepared in the above-mentioned way and containing metallized fibers as its high shrinkage component with the mixing ratio higher than that assuring a continuity of said fibers when seen from its theoretical probability, are distributed in a textile product, the latter can provide not only a superior antistatic performance, but also improved dyeing characteristics.

When the metallized fibers are utilized in the form of their filaments or alternatively of mixed filaments, they are frequently processed into textured yarns. For this purpose, it would be conceivable to process the metallized fibers prepared by the prior proposed technique and the textured and metallized yarns thus realized could be further processed through weaving or knitting into a final textile product. In this case, however, the metallized fibers must be subjected to a severe physical treatment such as strong twisting, edging or the like, so that part of the metallic coatings will frequently be scaled-off from the fibers to lesser or greater degree. Even if such phenomenon should not be invited, the tightness of the coating will become loosened under most circumstances.

It would be further conceivable to subject the conventionally textured yarns to the sensibilizing and activating steps and then deposited with metal in the chemical way. In this case, however, all the multifilaments are covered with metallic coatings and provide only a highly reduced effect for a certain fixed rate of fiber mixture. Therefore, a highly increased rate of fiber mixture must be employed for attainment of an equal result. As was briefly mentioned hereinbefore, an excessively increased rate of fiber mixture of the above kind will result generally in an adverse eifect upon the dyed characteristics of the final fibrous products.

It is therefore proposed as a preferable embodiment of the invention that the filaments are processed in such a way that they are, in advance of being textured, indeed,

processed only through limited steps of the whole metallizing process, or more specifically sensibilized and activated exclusively, and then, the thus partially processed filaments are dried, wound-up and mixed with a similar or different kind of plain or non-processed filaments and either in the state of filaments, or in the course of twisting the yarns prepared therefrom. The thus prepared m xedfiber multifilaments are then subjected to a conventional texturing step and then, preferably upon degreasing and dyeing, to the metal-depositing chemical step. In this way, the preactivated filament components only are metalcoated and contained in the textured yarns.

These textured yarns may be further processed mto final textile products by weaving, knitting or the l1ke conventional finishing technique. Or alternatively, the textured and activated yarns or textured yarns includmg activated filaments are fabricated into final products by weaving, knitting or like procedures. Then, these final products are subjected to a treatment in a metal-depositing bath for attaining the desired effect upon the preactlvated fibrous constituents only. It has been ascertained through practical experiments that the chemically deposited metal layer has an even coverage and a satisfactory depositing power.

The textured fabrics thus finished have a superior covering power, an efiicient hand feeling and stretchabrhty, as well as a favorable permanent antistatic characteristic which is provided by the very existence of practically continuous metal-coated filaments in place of short length fibers admixed to plain or non-metallized fibers or filaments as in the case of prior technique. In the finished textile fabrics according to the present invention, the textured yarns including metallized fibers or filaments must not be contained 100% or so. Accordmgto our experiments, it is sufficient to set the fiber mixing ratio to at least 0.01 wt. percent, preferably at least 0.1 wt. percent, for obtaining suflicient antistatic performance.

Thickness of the metal coating layer should be 0.01-l micron, preferably, 0.02.5-025 micron. When the thickness is less than 0.01 micron, the desired metallic appearance cannot practically be obtained, in additlon to the produced uneven metallic coating which has been realized only with substantial difiiculty in the control of the processing conditions. With coating thickness greater than one micron, the inherent physical properties of thermoplastic fibers will become rather considerably unfavorable and thus should be avoided.

The thickness of the metal coating on the fiber or filament to be used for the stretch yarn should preferably be less than 0.25 micron, since this kind of yarn may have a stretch or the rate of crimp elongation rate amounting to as high as 400%. With the stretch fabrics made of this kind of yarns, the rate may amount to 15-70%. The rate of stretch of the stretch knitted fabrics will be still larger. In these cases, use of heavier coating than above specified will lead to a substantial reduction of the depositing power resulted from repeated expansions and contractions encountered in practical usage of the yarns or th f b i It has been found that with the coated thickness amount- 6 ing to 0.025-025 micron the metallized fibers or filaments, contained in the yarns or fabrics represent acceptable values of strength and stretchability, in addition to the well-deposited formation of the metallic coating on the fiber, providing an efiicient conductivity as well as a satisfactory metallic appearance.

The preparatory treatments adopted in the inventive process in advance of the fiber-mixing, fiber-improving and the chemical metal-depositing steps and in the form of sensibilizing and activation steps have its object to adhere the fibrous material with catalytic noble metal. A representative process adopted for this purpose is to let the fiber surface adsorbed with a strong reducing agent and then the thus treated fibrous material is immersed in a catalyzer solution containing noble metal ions, so as to separate the metal onto the fiber surface, thus forming the desired catalyst. Or alternatively, the fibrous material is immersed in a bath solution containing a noble metal for adsorbing the latter, and then the fibrous material is treated in a reducing base so as to reduce the adsorbed noble metal which is deposited thereby on the surface of the fibrous material and in the form of the desired catalyst.

Generally speaking, the noble metal catalyst may be Ag, Pt, Pd, Au or the like. On the other hand, the reducing agent may be stannous chloride, hypophosphorous acid, hydrazine chloride, hydroquinone or the like.

The chemical coating bath may contain metal salt, reducing agent, main or auxiliary accelerator additive, pH- modifier and the like. The metallizing metal may be silver, copper, nickel, cobalt, zinc, chrominum, tin, gold, palladium or the like. Among others, copper, nickel and tin are suitable for the desired purpose, especially when considering the tightness, even stabilization, operating ease and the like of the produced metallizing coating.

As an example of the preferred composition of the chem1cal bath adapted for nickel coating, it may contain nickel ions derived from the chloride, sulphate or the like, or a combination thereof.

As the reducing agent, soluble hypophosphite such as sodium hypophosphite, calcium hypophosphite or the like may effectively be utilized. Hypohydrosulphite ions may be employed for the desired purpose.

Whena hypophosphite is used as the reducing agent, carboxyhc acid such as propionic acid, succinic acid or the like, or amino-carboxylic acid can be used as the main or auxiliary accelerator. As the complexing agent, hydroxycarboxylic acid such as tartaric acid, glycolic acid, lactic acid, citric acid or the like may be used. A most representative chemical bath adapted for the metal-depositing purpose comprises hypophosphite as the reducing agent; succinic acid as the accelerator; and acetic acid or sodium acetate as the buffer.

In the following, the invention will be described more in detail by way of several preferred numerical examples.

EXAMPLE 1 Acrylonitrile-series synthetic fibers, each being of 6 d., were dipped in a sensibilizing bath comprising:

Stannous chloride g 10 Hydrochloric acid cc 40 Water cc 1,000

for 3 minutes; washed sufficiently; dehydrated; and then immersed in an activating bath, comprising:

Palladium chloride g 0.5 Hydrochloric acid cc 5 Water cc 6,000

for 1 minute; washed thoroughly; dehydrated; and dried up. Thus, a mass of the activated fibers, called fiber mass (A) herein.

217 g. of the activated fiber mass (A) were dipped,

' 5.3 lit., for 6.5 minutes in a nickel-depositing bath of the 7 following composition per lit. and under the following treating conditions:

Nickel chloride g 20 Sodium hypophosphite g 27 Sodium succinate g 20 pH Temp. C 96 Bath ratio was 1:24; V/ A ratio (bath volume/surface area of the treated fiber mass) was 1/50. The mean thickness of the nickel coatings amounted 0.065 micron.

The thus nickel-deposited fibers were washed; dehydrated; dried up; and oiled and then mixedly spun at mixing ratios of 1% and 5%, respectively, with a mass of same kind of acrylonitrile fibers, each being again of 6 d., to provide 2/24 nm. of spun yarns. This product is called spun yarn (B) herein.

The activated fiber mass (A) was without being chemically metal-deposited, mixedly spun at mixing ratios of 1% and 5%, respectively, with a mass of same kind of acrylonitrile fibers, each being again 6 d., to produce 2/ 24 nm. of spun yarns. This product is called spun yarn (C) herein.

Said spun yarns (B) and (C) were dyed with Kayalon Fast Red R, manufactured and sold by a Japanese firm, Hodogaya Chemical Co., Ltd., Hodogaya, near Yokohama, Japan and believed to be under the following treating conditions:

Bath ratio 1:80; pH 4; 5% O.W.F.; temp. boiling point for 1 hr.

The results are shown in the following Table 1.

TABLE 1 Color tone of residual Sample Dyed color tone dyeing bath Blank l Rouge Red, dull, oily appearance. (B) 1% White reuge. Red, slightly white. (B) 5% Pink White red. (C) 1% Rouge Red, dull, oily appearance. (C) 6% Rouge, slightly dark D0.

1 6 d.-aerylonitrile series synthetic fibers.

TABLE 2 Color tone of Dyed residual dye- Sample color tone ing bath Remarks Blank l Red A-.. White, red (C) 1% Red do Favorably nickel-deposited (O) 5% Red" do Do.

I Said dyed fiber mass was treated with water under similar operating conditions of bath ratio, temperature and dipping period to those of said. nickel-depositing bath.

2 By virtue of the treating temperature higher than 00 C., a part of the dye was dissolved out, but all the three kinds of treating materials were dyed with similar color tone.

8 Acrylonitrile-series synthetic fibers were sensibilized with the same treating bath as above and then immersed for 5 minutes in an activating bath having the following composition:

Silver nitrate g 60 25 %-ammonia aqua-solution ml 20 Water lit 1 The thus activated fiber mass was treated wtih a copper-depositing chemical bath containing non-electrolytic metal-depositing composition, manufactured and sold by Japanese firm, Asahi Dow Company, Limited, Tokyo, Japan. Similar results as above were obtained.

EXAMPLE 2 A tow of 3 d.-acrylic synthetic fibers was treated in a turbo-stapler at 140 C. with 1.25 times elongation, to provide a sliver. This sliver was immersed in a sensibilizing bath containing '10 g. of stannous chloride, 400 cc. of hydrochloric acid and 1,000 cc. of water, for 5 minutes. Then, the fibrous material thus treated was washed sufficiently with water; immersed in an activating bath containing 0.5 g. of palladium chloride, 5 cc. of hydrochloric acid and water 6,000 cc. for 5 minutes; washed with water; oiled and dried up. Then, it was subjected to a conventional shrinking process. This activated and high-shrunk fiber mass was admixed with similar 3 d.- acrylic high contracted and at a mixing ratio of 10% so as to provide a sliver. This sliver was mixed with 3 d.- low-shrunk sliver on a mixing gill in such a manner that the content of the activated, high-shrunk fiber component amounted to 5%. From this, spun yarns, 2/4'8 nm., were prepared.

These yarns were dyed at 100 C. for 1 hour and subjected to a shrinking of 18.0% to provide bulky yarns which were then immersed in a nickel-depositing bath having the following composition per liter:

Nickel chloride g 20 Sodium hypophosphite g 27 Sodium succinate g Water lit 1 pH 3 5 at 98 C. for 6 minutes. In this way, evenly mixed, acrylic bulky yarns having activated and favorably nickel-deposited fiber component were obtained. In case of monofilaments, 3 d.-1/ 48 nm., the necessary mixing ratio for attaining a theoretical continuation with a reliable probability of nickel-deposited fibers can be determined in the following way:

9,000 m./48 nm.=l98 d.

When these nickel-deposited fiber-containing acrylic bulky yarns were woven or knitted to final textile products which have an electrical surface resistance: 2X10 ohms at 22 0; RH 65%. The initial voltage 12.2 mv. was measured on an Honest-Meter. Covering power and hand feeling were superior.

'Next, these acrylic bulky yarns containing nickel-deposited fibers as warps were mixedly woven with those containing none of nickel-deposited fibers in the form of wefts and in the ratio of 1:3. The overall containing ratio of the nickel-deposited fibers amounted to 1.7%. Surface resistance: 4 10 ohms at 22 C., RH: 65 The initial voltage on Honest-Meter: 17.8 mv. The developed color tone was highly superior.

EXAMPLE 3 A tow of 6 d.-acrylic fibers was subjected to a thermal shrinking step and then subjected to an elongation of 1.3 times length in a boiling water. These fiber filaments were cut into a mean length of 76 mm. These cut fibers were activated in the same manner as in the foregoing Example 2, so as to provide activated and highshrinking acrylic fibers which were then mixed with similar fibers prepared in the similar way, but not activated, at a mixing ratio of 6% of the former. This high-shrinking sliver was mixed at a ratio of 1:1 with a corresponding, yet low-shrinking tow in a mixing gill, so as to provide filaments, each d., 1/ 24 nm.

These filaments were mixed with similar filaments, yet containing no activated fibers of 5 d., 1/24 nm., to provide spun yarns of 2/24.

The necessary mixing ratio for attaining a theoretical continuity of the nickel-coated fibers may be:

9,000-z-24 nm.=375 d.

These spun yarns were dyed at 100 C. for 1 hour, and then subjected to a contraction of 16%, so as to provide bulky yarns. These yarns were then nickel-deposited as in the foregoing Example 2 in a chemical bath as before. In this way, dyed and bulkied acrylic yarns including 3% of nickel-deposited fibers were obtained.

A mixed-fiber knitted product composed of said both kinds bulky yarns with a mixing ratio of 1:3 and containing about 1% of nickel-deposited fibers represented a surface electrical resistancez4 ohms. Initial voltage on Honest-Meter:20.5 mv. The antistatic characteristics and dyed color tone were highly superior.

In the above example, the surface electrical resistance was measured at -22 C. with RH:65%.

Honest-Meter was manufactured and sold by a Japanese firm: Shishido Shokai. Applied voltage was +10 kv. for 30 seconds. The initial voltage of the yarns containing none of metal-deposited fibers amounted to 38 mv.

EXAMPLE 4 Acrylonitrile multi-filaments, 1O d./55, having a composition of:

were spun, dried, twisted and wound up. Then, these filaments were passed through several steps of degreasing, water-washing, sensibilizing, second water-washing, activating, third water-washing and drying and then wound up again on a bobbin.

The sensibilizing bath comprises 10 g. of stannous chloride, 40 cc. of'hydrochloric acid and 1,000 cc. of water, while the activating bath contained:5 g. of palladium chloride, 5 cc. of hydrochloric acid and 6,000 cc. of water, being adapted for one pass operation for both cases.

These activated acrylic multi-filaments were mixed with those, non-activated, so as to provide 40 d./ 20 f. and then prefabricated into false twisted threads under the following operating conditions: peripheral speed of feed roller 68 m./ min., heater temperature 180 C., revolutions of spindle 115,000 r.p.m., and delivery roller speed 70 m./min.

These false twisted threads were continuously treated under their slackened condition in a nickel-depositing chemical bath containing per I lit. of the bath solution, 20 g. of nickel chloride, 27 g. of hypophosphite, 29 g. of sodium succinate and 1 lit. of water, pH:5, 80 C., so as to provide acrylic false twisted threads containing nickel-coated threads. The immersion period in this case in the chemically depositing bath was adjusted to 4 minutes and the consumed nickeland hypophosphite ions were continuously supplemented.

The thus resulted acrylic filaments nickel-deposited and false-twisted and those of non-metal coated were utilized as warps, and non-nickel-coated acrylic spun yarns were utilized as wefts, were processed into functional stretch fabrics which showed superior stretchability, covering performance and antistatic characteristics.

FRICTIONAL STATIC VOLTAGE (KILOVOLTS) 1 I: No. of repeated washes II: Duration of friction min 0. 5 5 0. 5 5

Sample:

Mlx ratio: 1%, V 45 38 6 360 450 268 Blank including no metallized fibers 81 59 9 840 1, 080 910 1 Friction element: calfskin, RH 456, 30 0.; measuring instrument: rotary static tester.

2 After washing; machine washing for 10 minutes; water rinsing 10 min.; cleaning agent: New Beads manufactured and sold by Kao Soap K.K., Tokyo.

3 5 minutes friction and 1 minute resting.

EXAMPLE 5 Nickel chloride percent 19.6 Sodium hypophosphite do 23.7 Lactic acid g 27.0 Propionic acid g 2.2 Water lit 1 under pH 5 at C. for 1 hour.

It was ascertained that the already activated, false twisted acrylic multi-filaments were only nickel-deposited. The resulting fabric showed favorable stretchability and superior antistatic characteristics.

EXAMPLE 6 66 nylon-multifilaments, 11 d./ 5 f., were spun, stretched, twisted and once wound up on a bobbin. Then, it was passed successively and continuously through several baths of degreasing, Water-washing, sensibilizing, water-washing and drying, and once again wound up. The compositions of the sensibilizing and activating were same as in the foregoing Example 1. Duration of pass was adjusted to 3 minutes.

The thus activated nylon multifilaments were mixed with plain or non-activated nylon multifilaments to such of fibrous mixture, 70 d./ 32 f. This mixture so treated was subjected to a stulfer step and then wound up.

The thus stulfered nylon filaments were degreased, and then passed again through a sensibilizing chemical bath for one minute, washed with water, and immersed continuously for 10 minutes in a copper-coating chemical bath containing a nonelectrolytic copper-depositing composition manufactured and sold by Asahi Dow Co., Ltd. Then, it was washed with water, dried up and wound up again. In this way, stuffered nylon yarns include coppercoated filaments.

These yarns were utilized as warps and acrylic spun yarns were utilized as wefts, the fiber mixture rate having been adjusted to 2%. The thus prepared fabric had a superior covering performance and a favorable dye color tone.

Main components of the copper-depositing composition above-mentioned are believed to include copper sulfate, Formalin and sodium sulfate, added with small amounts of caustic soda and sodium carbonate.

EXAMPLE 7 6 d.-acrylonitrile-series synthetic fibers, activated in the same manner as in the forgoing Example 1 were mixed with same kind of synthetic fibers, non-activated, at a mixing ratio of 5% and the fibrous mixture was vatted in a bath solution including Cathilon Biue NBLH, manufactured and sold by Hodogaya Chemical Co., Ltd., at 0.03% 0.W.F.

This dyed fiber mixture was then immersed in a golddepositing chemical bath containing per lit. silver nitrate 22.2 g.; 25%-ammonia aqua-solution 30 ml.; 37%-Formalin 2.5 ml.; degradation inhibitor composition including sodium sulfate and ethyl alcohol, at normal temperature for about 5 minutes. The resulting products had an eflicient conductivity as a whole, and the well-developed color tone was of saxe blue. Surface electric resistance amounted to 6.5 l ohms. Initial voltage on Honest- Tester amounted to 20.5 mv., 20 C., RH 25%. This was then dehydrated at 20 C., RH 40%. Antistatic performance was superior. No sparks or discharge noises were encountered while undressing (underwear was made of cotton).

On the other hand, activated, 6 d-acrylonitrile fibers were mixed at with similar, yet non-activated fibers, and then silver-deposited and then dyed. Substantial degree of fading of the dye during the dyening process was encountered. Antistatic characteristics were considerably inferior with practically no dyed effect.

EXAMPLE 8 Polyester multifilaments, 30 d./ 10 f., were spun out, stretched, false twisted and activated in the same manner as in the foregoing Example 4.

Similar multifilaments, 120 d./40 f., non-activated, were prepared and mixed with the first multifilaments, the mixed product becoming 150 d./50 f. This fibrous mixture was subjected to a false twisting under the following conditions: Revolutions of spindle 2480 t./meter; first heater temperature 220 C.; second heater temperature 190 C.; first feed rate plus 4%; second feed rate plus 25%; take up rate minus 22%.

These false twisted polyester yarns were used as wefts, while acrylic multifilaments, 150 d./50 f., were utilized as warps, to fabricate a woven fabric which was then immersed in a chemical bath containing:

at pH: 5.0, and 60 C. for 6 minutes so as to activate. These activated polyester multifilaments were only found as nickel-deposited. Stretch performances and antiflaming characteristics were highly superior.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process for the manufacture of a fibrous mixture having superior antistatic characteristics comprising the steps of (l) subjecting a fibrous material to deposition of a noble metal catalyst on the surface of said fibrous material, thereby sensitizing, conditioning and activating said surface,

(2) drying the thus catalyst-deposited fibrous material,

(3) mixing the thus catalyst-deposited and dried fibrous material with a non-catalyzed fibrous material forming a fibrous mixture, and

(4) subjecting said mixture to a metal-deposition treatment in a chemical bath containing a metal selected from the group consisting of silver, copper, nickel, tin, palladium, cobalt, zinc, chromium, and gold, thereby depositing said metal exclusively on the fibrous material in said mixture containing said deposited catalyst.

2. The process of claim 1, wherein the fibrous mixture is dyed after catalyst deposition and before metal deposition.

3. The process of claim 1, wherein the fibrous mixture is a yarn or like extended body and is bulked, by stretching from 1.1 to 1.5 times at from to C. and.

subsequently contracted by from 5 to 40% of its stretched length, after catalyst deposition, and before metal deposition.

4. The process as claimed in claim 1, wherein said fibrous mixture is subjected to a false-twist texturing step.

5. The process of claim 1, wherein said metal is selected from the group consisting of nickel, copper and tin.

6. The process of claim 1, wherein said metal catalyst is selected from the group consisting of platinum, palladium, gold and silver.

7. The process of claim 1, wherein said metal-depositing treating comprises electrolessly depositing said metal from said chemical bath.

8. The process of claim 1, wherein said deposition of said noble metal catalyst comprises depositing a noble metal on said fibrous material by reducing a salt of said noble metal.

9. The process of claim 8, wherein said reducing agent is selected from the group consisting of stannous chloride, hypophosphorus acid, an alkali metal hypophosphite, an alkaline earth metal hypophosphite, hydrazine hydrochloride, and hydroquinone.

10. The proces as claimed in claim 1, wherein the thickness of the deposited metal ranges from 0.01 to 1.00 micron thick.

=11. The process of claim 10, wherein the thickness of the deposited metal ranges from 0.025 to 0.25 micron thick.

12. The process as claimed in claim 1, wherein the amount of metal-deposit on the fibrous material is at least 0.01% by weight.

13. The process of claim 12, wherein the amount of metal-deposited fibrous material is at least 0.1% by weight.

14. The process of claim 1, wherein said fibrous material is a fiber selected from the group consisting of the acetates, triacetates, cuprammonium rayons, polyamides, polyesters, polyvinyls, polyacrylonitriles, polyvinyl chlorides, polyvinylidene chlorides, polyolefins, polyurethanes, and copolymers thereof.

15. The process of claim 14, wherein said fiber is selected from the group consisting of polyvinyl chlorides, polyvinylidene chlorides, and polyacrylonitrile.

References Cited UNITED STATES PATENTS 2,862,783 12/1958 Drummond 117-47 A 3,058,845 10/1962 Hendricks 117-37 R 3,108,897 10/1963 Hamiter 117-160 R 3,315,285 4/1967 Farmer 11747 A ALFRED L. LEAVITT, Primary Examiner M. F. ESPOSITO, Assistant Examiner U.S. Cl. X.R.

117-7, 37 R, 47 A, 138.8 U, 213; 161-169 

